1. Field of the Invention
The invention relates to metal working processes and more particularly to improved HIP Bonding processes particularly suited for bonding austenitic materials.
2. Description of the Prior Art
Specialized Pressure Bonding techniques are widely available in the prior art. For example, U.S. Pat. No. 4,628,008 issued to Conolly discusses the assembly of "sticks" to form a defect-immunized major component such as a turbine disc or rotor. Prior art techniques are further illustrated by U.S. Pat. No. 4,603,801, issued to Wan which discloses an interference fit seal to prevent the pressure transmitting medium from entering the interfaces of the HIP bonding joint. The pressure transmitting medium is further described as a thick, high-viscosity material, such as molten glass, which is thick enough not to penetrate the interference fit seal. Other prior art techniques are illustrated by U.S. Pat. No. 4,485,961, issued to Ekbon, which illustrates a method for creating a weld using the HIP bonding technique. The joint is covered by a powder of similar composition to the material being joined, which is in turn covered by various glass-like compositions that act as a pressure transmitting medium. At elevated temperatures, the glass composition melts and provides a sealing boundary. The powder covering the joints is fused during the HIP Bonding process to complete the weld.
A method for sheathing tubular nuclear fuel elements is disclosed in U.S. Pat. No. 3,559,274, issued to Granata. Zircalloy sheathing tube is shrink fitted inside of a uranium pipe. After shrink fitting, the assembly is heated and the outside is cooled so as to form a diffusion bond at the interface. The fusion is due to the expansion of the sheath, contraction of the tube, and the heat at the interface.